The cosmopolitan citizens of Chicago are less than astonished to learn that the heir to the Hyatt hotel fortune, Col. James Pritzker, will henceforth be known as Jennifer Natalya Pritzker.

The 63-year-old billionaire heir — a cousin ofPresident Obama’s new commerce secretary, Penny Pritzker — had been wearing a long ponytail since retiring from the Army and the National Guard. And lately, she’s been sporting diamond stud earrings.

“It hasn’t caused much of a stir in Chicago because he’s always been a little uncomfortable in his skin,” one insensitive socialite, who still refers to Pritzker as a he, told The Post’s Richard Johnson. “That’s why they [the family] put him in the military.”

The retired lieutenant colonel is president and CEO of Tawani Enterprises and a board member of Squadron Capital, a private-equity firm in Connecticut. Forbes lists Pritzker as having a net worth of $1.5 billion.

An inquiry from Crain’s Chicago Business prompted the very private Pritzker, a divorced father of two sons and a daughter, to announce she was legally changing her name as of Aug. 16: “This change will reflect the beliefs of her true identity that she has held privately and will now share publicly. Pritzker now identifies herself as a woman for all business and personal undertakings.” A rep wouldn’t discuss her sexual orientation or any possible hormone or surgical procedures.

Jennifer is one of 10 billionaire members of the extended Pritzker family — who sold a controlling stake in conglomerate Marmon Holdings to Warren Buffett’s Berkshire Hathaway for $4.5 billion. Her late father, Robert Pritzker, and uncle, Jay Pritzker, created Marmon and grew the Hyatt hotel chain.

Jennifer put herself in the spotlight with her controversial attempt to buy the beautiful 1927 Harley Clarke Mansion in Evanston, Ill., and convert it to a boutique hotel. Protesters convinced the City Council on July 22 to vote it down. “The next month she came out,” said a local.